U.S. patent number 11,005,328 [Application Number 16/028,459] was granted by the patent office on 2021-05-11 for motor.
This patent grant is currently assigned to NIDEC CORPORATION. The grantee listed for this patent is Nidec Corporation. Invention is credited to Yuya Horii, Kohei Kurazono, Tsuyoshi Yasumura.
![](/patent/grant/11005328/US11005328-20210511-D00000.png)
![](/patent/grant/11005328/US11005328-20210511-D00001.png)
![](/patent/grant/11005328/US11005328-20210511-D00002.png)
![](/patent/grant/11005328/US11005328-20210511-D00003.png)
![](/patent/grant/11005328/US11005328-20210511-D00004.png)
![](/patent/grant/11005328/US11005328-20210511-D00005.png)
![](/patent/grant/11005328/US11005328-20210511-D00006.png)
United States Patent |
11,005,328 |
Horii , et al. |
May 11, 2021 |
Motor
Abstract
A motor includes a bearing housing, a stator, and a fixing
member. The stator includes a stator core, an insulator, and a
lead. The insulator is an insulating body that covers at least a
portion of the stator core. The lead is wound around the stator
core with the insulator interposed therebetween. The bearing
housing includes a first bearing holding portion and a second
bearing holding portion that hold two bearings; and an intermediate
portion that is positioned between the first bearing holding
portion and the second bearing holding portion in the vertical
direction. The lower surface of the fixing member is in contact
with the upper surface of the stator. The fixing member is fixed at
a position opposite the intermediate portion in the radial
direction. As a result, the displacement of the stator relative to
the bearing housing is suppressed.
Inventors: |
Horii; Yuya (Kyoto,
JP), Kurazono; Kohei (Kyoto, JP), Yasumura;
Tsuyoshi (Kyoto, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Nidec Corporation |
Kyoto |
N/A |
JP |
|
|
Assignee: |
NIDEC CORPORATION (Kyoto,
JP)
|
Family
ID: |
1000005545028 |
Appl.
No.: |
16/028,459 |
Filed: |
July 6, 2018 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20190020241 A1 |
Jan 17, 2019 |
|
Foreign Application Priority Data
|
|
|
|
|
Jul 14, 2017 [JP] |
|
|
JP2017-138130 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02K
15/14 (20130101); H02K 1/16 (20130101); F16C
35/067 (20130101); F16C 25/06 (20130101); H02K
1/185 (20130101); H02K 5/163 (20130101); H02K
1/187 (20130101); H02K 21/22 (20130101); F16C
2380/26 (20130101); H02K 5/161 (20130101); H02K
5/16 (20130101); F16C 25/083 (20130101); H02K
5/1735 (20130101) |
Current International
Class: |
H02K
5/16 (20060101); F16C 35/067 (20060101); H02K
1/16 (20060101); F16C 25/06 (20060101); H02K
21/22 (20060101); H02K 15/14 (20060101); H02K
5/173 (20060101); H02K 1/18 (20060101); F16C
25/08 (20060101) |
Field of
Search: |
;310/89,90 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1549424 |
|
Nov 2004 |
|
CN |
|
102170213 |
|
Aug 2011 |
|
CN |
|
11-252878 |
|
Sep 1999 |
|
JP |
|
2006-254651 |
|
Sep 2006 |
|
JP |
|
2013-165620 |
|
Aug 2013 |
|
JP |
|
Primary Examiner: Nash; Gary A
Attorney, Agent or Firm: Keating & Bennett, LLP
Claims
What is claimed is:
1. A motor comprising: a stationary portion; and a rotary portion
that is supported so as to be rotatable about a vertically
extending center axis relative to the stationary portion, wherein
the stationary portion includes a cylindrical bearing housing that
extends in an axial direction around the center axis, and a stator
and a fixing member that are disposed outside the bearing housing
in a radial direction, wherein the stator includes a stator core
that is a magnetic body, an insulator that is an insulating body
that covers at least a portion of the stator core, and a lead that
is wound around the stator core with the insulator interposed
therebetween, wherein the bearing housing includes a first bearing
holding portion and a second bearing holding portion that hold two
bearings, and an intermediate portion that is positioned between
the first bearing holding portion and the second bearing holding
portion in a vertical direction, wherein a lower surface of the
fixing member is in contact with an upper surface of the stator,
and wherein the fixing member is fixed at a position opposite the
intermediate portion in the radial direction.
2. The motor according to claim 1, wherein the bearing housing is
opposite the stator core in the radial direction with a gap
interposed therebetween, and wherein the gap is filled with an
elastic member.
3. The motor according to claim 2, wherein the stator core includes
a plurality of recessed portions in an inner circumferential
surface thereof, the plurality of recessed portions being recessed
outward in the radial direction, and wherein a portion of the
elastic member is positioned inside the recessed portions.
4. The motor according to claim 2, wherein the fixing member covers
an upper side of the gap.
5. The motor according to claim 2, wherein the bearing housing
includes a step surface that has a circular ring shape, the step
surface being opposite a lower surface of the stator core in the
axial direction, and wherein a portion of the elastic member is
interposed between the lower surface of the stator core and the
step surface.
6. The motor according to claim 1, wherein the bearing housing and
the fixing member are formed of an identical non-magnetic metal
material.
7. The motor according to claim 1, wherein the fixing member is a
ring member that has an annular shape.
8. The motor according to claim 1, wherein the fixing member is a
ring member that has an annular shape in which a portion is
open.
9. The motor according to claim 1, wherein a thickness of the
bearing housing in the radial direction at the intermediate portion
is larger than a thickness of the bearing housing in the radial
direction at the first bearing holding portion.
10. The motor according to claim 1, wherein an outer
circumferential surface of the bearing housing includes a first
outer circumferential surface on which the fixing member is
disposed and a second outer circumferential surface that is
positioned above the first outer circumferential surface, and
wherein a diameter of the first outer circumferential surface with
the center axis as a center is larger than a diameter of the second
outer circumferential surface.
11. The motor according to claim 1, wherein the bearing housing
includes a step surface that has a circular ring shape, the step
surface being opposite a lower surface of the stator core in the
axial direction, and wherein a radius of an outer edge of the
fixing member with the center axis as a center is larger than a
radius of an outer edge of the step surface.
12. The motor according to claim 1, wherein the stator includes an
annular groove portion on the upper surface of the stator, the
groove portion being recessed downward in the axial direction, and
wherein at least a portion of the fixing member is housed in the
groove portion.
13. The motor according to claim 12, wherein the groove portion is
formed by the outer circumferential surface of the bearing housing,
the upper surface of the stator core, and an inner circumferential
surface of the insulator, and wherein the lower surface of the
fixing member is in contact with the upper surface of the stator
core.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of priority to Japanese Patent
Application No. 2017-138130 filed on Jul. 14, 2017. The entire
contents of this application are hereby incorporated herein by
reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motor.
2. Description of the Related Art
There is a known motor that has a structure in which a bearing is
held by a cylindrical bearing housing and a stator is fixed to the
outer circumferential surface of the bearing housing. A known motor
is described in, for example, Japanese Unexamined Patent
Application Publication No. 2013-165620.
A motor generates torque by using magnetic attraction force and
magnetic repulsive force generated between a stator and a rotor.
Thus, the magnetic attraction force and the magnetic repulsive
force sometimes cause the stator to vibrate during driving of the
motor. The vibration may become a factor of noise. In order to
suppress the vibration of a stator, for example, it is conceivable
to interpose an elastic adhesive capable of absorbing vibration
between a bearing housing and the stator. However, the elastic
adhesive requires a long time for curing. Therefore, it is required
to suppress the displacement of the position of the stator relative
to the bearing housing during curing of the elastic adhesive.
Regardless of the presence/absence of the elastic adhesive, there
is a requirement to suppress the displacement of the position of
the stator relative to the bearing housing.
SUMMARY OF THE INVENTION
According to an embodiment as an example of the present disclosure,
a motor includes a stationary portion and a rotary portion that is
supported so as to be rotatable about a vertically extending center
axis relative to the stationary portion. The stationary portion
includes a cylindrical bearing housing that extends in an axial
direction around the center axis; and a stator and a fixing member
that are disposed outside the bearing housing in a radial
direction. The stator includes a stator core that is a magnetic
body, an insulator that is an insulating body that covers at least
a portion of the stator core, and a lead that is wound around the
stator core with the insulator interposed therebetween. The bearing
housing includes a first bearing holding portion and a second
bearing holding portion that hold two bearings; and an intermediate
portion that is positioned between the first bearing holding
portion and the second bearing holding portion in a vertical
direction. A lower surface of the fixing member is in contact with
an upper surface of the stator. The fixing member is fixed at a
position opposite the intermediate portion in the radial
direction.
The above and other elements, features, steps, characteristics and
advantages of the present disclosure will become more apparent from
the following detailed description of the preferred embodiments
with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal sectional view of a motor.
FIG. 2 is a longitudinal sectional view of a bearing housing.
FIG. 3 is a partial sectional view of the bearing housing, a
stator, and a fixing member.
FIG. 4 is a partial perspective view of the bearing housing, the
stator, and the fixing member, taken along a plane that includes a
center axis.
FIG. 5 is a top view of the bearing housing and the stator.
FIG. 6 is a perspective view of a bearing housing, a stator, and a
fixing member according to a modification.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, an embodiment as an example of the present disclosure
will be described with reference to the drawings. In the present
disclosure, the direction parallel to the center axis of a motor,
the direction perpendicular to the center axis of the motor, and
the direction along a circular arc with the center axis of the
motor as the center thereof are referred to as the "axial
direction", the "radial direction", and the "circumferential
direction", respectively. In addition, in the present disclosure,
the shape or the positional relationship of each component will be
described on the basis of the axial direction being the vertical
direction and a side where a fixing member is disposed with respect
to a stator core being the upper side. However, the vertical
direction is thus defined merely for convenience of description,
and orientations of the motor according to the present disclosure
during manufacturing and usage thereof are not limited by the
definition.
In the present disclosure, the "parallel direction" includes a
substantially parallel direction. In addition, in the present
disclosure, the "perpendicular direction" includes a substantially
perpendicular direction.
FIG. 1 is a longitudinal sectional view of a motor 1 according to
one embodiment as an example of the present disclosure. FIG. 2 is a
longitudinal sectional view of a bearing housing 22. As illustrated
in FIG. 1, the motor 1 includes a stationary portion 2 and a rotary
portion 3. The stationary portion 2 is fixed to a frame body of a
machine (hereinafter referred to as the "real machine") on which
the motor 1 is mounted. The rotary portion 3 is supported so as to
be rotatable relative to the stationary portion 2.
The stationary portion 2 according to the present embodiment
includes a base plate 21, the bearing housing 22, a pair of
bearings 23, a stator 24, a circuit board 25, and a fixing member
70.
The base plate 21 is a plate-shaped member that extends
perpendicularly relative to a center axis 9. The base plate 21 is
fixed to the frame body of the real machine by, for example,
screwing. The base plate 21 includes a circular hole 210 at the
center thereof. In addition, the base plate 21 includes, at the
circumference of the circular hole 210, a cylindrical holding
portion 211 that extends upward. A material of the base plate 21
is, for example, metal such as iron. However, the material of the
base plate 21 is not limited to metal and may be resin.
The bearing housing 22 is a member that holds the pair of bearings
23. A material of the bearing housing 22 is, for example, metal
such as stainless steel, brass, or the like. However, the material
of the bearing housing 22 is not limited to metal and may be resin.
The bearing housing 22 cylindrically extends in the axial direction
around the center axis 9. The lower end portion of the bearing
housing 22 is inserted into the circular hole 210 of the base plate
21 and fixed to the holding portion 211.
The pair of two bearings 23 are positioned inside the bearing
housing 22 in the radial direction. The bearing housing 22 includes
a first bearing holding portion 501 and a second bearing holding
portion 502. The first bearing holding portion 501 and the second
bearing holding portion 502 are disposed so as to be spaced from
each other in the vertical direction. The two bearings 23 are
respectively held by the first bearing holding portion 501 and the
second bearing holding portion 502. The bearings 23 are, for
example, ball bearings. An outer race of each of the bearings 23 is
fixed to the inner circumferential surface of the bearing housing
22. An inner race of each of the bearings 23 is fixed to the outer
circumferential surface of a shaft 31, which will be described
later. In addition, the bearing housing 22 includes an intermediate
portion 221 between the first bearing holding portion 501 and the
second bearing holding portion 502 in the vertical direction. In
the present embodiment, a preload spring 231 is provided between
the bearing 23 on the upper side and the intermediate portion 221.
The outer race of the bearing 23 on the upper side is pressed in
the axial direction by the preload spring 231. As a result, the
bearing 23 is positioned in the axial direction.
The stator 24 is an armature that generates a magnetic flux in
response to a driving current. The stator 24 is disposed outside
the bearing housing 22 in the radial direction. As illustrated in
FIG. 1, the stator 24 includes a stator core 41, an insulator 42,
and a coil 43.
The stator core 41 is a magnetic body. The stator core 41 is, for
example, a laminated steel sheet. The stator core 41 includes a
core back 411 that has a circular ring shape and a plurality of
teeth 412. The core back 411 is fixed to the outer circumferential
surface of the bearing housing 22. The plurality of teeth 412
protrude from the core back 411 outward in the radial direction.
The insulator 42 is an insulating body. A material of the insulator
42 is, for example, resin. The insulator 42 covers at least a
portion of the stator core 41. The coil 43 is constituted by a lead
wound around the teeth 412 with the insulator 42 interposed
therebetween.
The stationary portion 2 includes the fixing member 70 disposed
outside the bearing housing 22 in the radial direction. The stator
24 is fixed to the outer circumferential surface of the bearing
housing 22 by the fixing member 70. The fixing member 70 is
disposed above the stator 24 and outside the bearing housing 22 in
the radial direction and fixes the position of the stator 24.
Specifically, the lower surface of the fixing member 70 is in
contact with the upper surface of the stator 24. The fixing member
70 is fixed at a position opposite the intermediate portion 221 of
the bearing housing 22 in the radial direction.
The circuit board 25 is disposed above the base plate 21 and below
the stator 24 so as to be substantially perpendicular to the center
axis 9. The circuit board 25 is fixed to, for example, the
insulator 42. An electric circuit for supplying a driving current
to the coil 43 is mounted on the circuit board 25. An end portion
of the lead that constitutes the coil 43 is electrically connected
to a terminal disposed on the circuit board 25.
The rotary portion 3 according to the present embodiment includes
the shaft 31, a fixing ring 32, a hub 33, a rotor magnet 34, and a
rotor holder 35.
The shaft 31 is a columnar member disposed along the center axis 9.
A material of the shaft 31 is, for example, metal such as stainless
steel and the like. The shaft 31 is supported by the pair of
bearings 23 so as to be rotatable about the center axis 9. An upper
end portion of the shaft 31 is positioned above the bearing 23 on
the upper side. The fixing ring 32 is a metal member that has a
circular ring shape. The fixing ring 32 is fixed to the upper end
portion of the shaft 31.
The rotor holder 35 is a member that has a circular ring shape and
that holds the rotor magnet 34. A material of the rotor holder 35
is, for example, metal such as iron and the like. The hub 33 is a
member that holds the rotor holder 35. The hub 33 includes a disc
portion 331 and a cylinder portion 332. The disc portion 331 covers
the upper side of the stator 24. The inner circumferential part of
the disc portion 331 is fixed to the fixing ring 32. That is, the
hub 33 is fixed to the shaft 31 with the fixing ring 32 interposed
therebetween. The cylinder portion 332 extends downward from the
outer circumferential part of the disc portion 331.
The rotor holder 35 is fixed to the inner circumferential surface
of the cylinder portion 332. The rotor magnet 34 is fixed to the
inner circumferential surface of the rotor holder 35. The rotor
magnet 34 may be one magnet that has a circular ring shape or may
be a plurality of magnets arranged in the circumferential
direction. The outer end surface of each of the teeth 412 in the
radial direction and the inner surface of the rotor magnet 34 in
the radial direction are opposite each other in the radial
direction with a small gap interposed therebetween. The inner
surface of the rotor magnet 34 in the radial direction is
magnetized such that the north pole and the south pole are
alternately arranged in the circumferential direction.
When a driving current is supplied from the circuit board 25 to the
coil 43 of the stator 24 in the motor 1, a magnetic flux is
generated at each of the teeth 412. Then, torque in the
circumferential direction is generated by a rotating magnetic field
generated between each of the teeth 412 and the rotor magnet 34. As
a result, the rotary portion 3 is rotated about the center axis 9
relative to the stationary portion 2.
Next, a fixing structure of the bearing housing 22, the stator 24,
and the fixing member 70 will be described in detail. FIG. 3 is a
partial sectional view of the bearing housing 22, the stator 24,
and the fixing member 70. FIG. 4 is a partial perspective view of
the bearing housing 22, the stator 24, and the fixing member 70,
taken along a plane that includes the center axis 9. FIG. 5 is a
top view of the bearing housing 22 and the stator 24.
As illustrated in FIG. 2, the bearing housing 22 includes the first
bearing holding portion 501, the second bearing holding portion
502, a first outer circumferential surface 51, a second outer
circumferential surface 52, the intermediate portion 221, and a
step surface 222. The first bearing holding portion 501 is a
portion in which one of the bearings 23 is held inside the bearing
housing 22. Specifically, the outer race of the bearing 23 is fixed
to the inner circumferential surface of the bearing housing 22,
which is the first bearing holding portion 501. In order to
position the bearing 23 relative to the bearing housing 22 with
high accuracy, the inner circumferential surface of the first
bearing holding portion 501 is preferably processed accurately to
be completely round and processed to have small surface
roughness.
The second bearing holding portion 502 is a portion in which one of
the bearings 23 is held inside the bearing housing 22. The second
bearing holding portion 502 is positioned below the first bearing
holding portion 501 in the axial direction. Specifically, the outer
race of the bearing 23 is fixed to the inner circumferential
surface of the bearing housing 22, which is the second bearing
holding portion 502. Similarly to the inner circumferential surface
of the first bearing holding portion 501, the inner circumferential
surface of the second bearing holding portion 502 is preferably
processed accurately to be completely round and processed to have
small surface roughness.
The intermediate portion 221 is provided between the first bearing
holding portion 501 and the second bearing holding portion 502 in
the vertical direction. The bearing housing 22 has a cylindrical
shape that passes through the center axis 9. The bearing housing 22
has a thickness in the radial direction. In the present embodiment,
the thickness of the bearing housing 22 in the radial direction at
the intermediate portion 221 is larger than the thickness of the
bearing housing 22 in the radial direction at the first bearing
holding portion 501. That is, the rigidity of the bearing housing
22 at the intermediate portion 221 is larger than the rigidity of
the bearing housing 22 at the first bearing holding portion
501.
At least a portion of the first outer circumferential surface 51 is
a portion of the outer circumferential surface of the bearing
housing 22 at the intermediate portion 221. That is, a surface of
at least a portion of the first outer circumferential surface 51 is
a surface positioned outside the intermediate portion 221 in the
radial direction. The first outer circumferential surface 51 is a
portion of the outer circumferential surface of the bearing housing
22 opposite the stator core 41 in the radial direction. In
addition, the first outer circumferential surface 51 is a portion
of the outer circumferential surface of the bearing housing 22
opposite the fixing member 70 in the radial direction.
The second outer circumferential surface 52 is a portion of the
outer circumferential surface of the bearing housing 22 along which
the fixing member 70 passes when being inserted. That is, the
second outer circumferential surface 52 is positioned above the
first outer circumferential surface 51 in the axial direction.
Here, the diameter of the first outer circumferential surface 51
with the center axis 9 as the center is larger than that of the
second outer circumferential surface 52. The diameter of the second
outer circumferential surface 52 is smaller than the inner diameter
of the fixing member 70. Due to the diameter of the second outer
circumferential surface 52 smaller than the inner diameter of the
fixing member 70, it is possible to avoid damage of the outer
circumferential surface of the bearing housing 22 and the bearing
housing 22 itself during disposing the fixing member 70 at the
first outer circumferential surface 51. A gap between the second
outer circumferential surface 52 and the inner circumferential
surface of the fixing member 70 is preferably sufficiently large. A
large gap enables the fixing member 70 to be disposed on the upper
surface of the stator 24 without catching the bearing housing
22.
In the present embodiment, the fixing member 70 is fixed to the
bearing housing 22 by press-fitting. Specifically, the inner
circumferential surface of the fixing member 70 is fixed by
press-fitting to the first outer circumferential surface 51 of the
outer circumferential surface of the bearing housing 22 positioned
at the intermediate portion 221. The fixing member 70 is not
necessarily fixed by press-fitting. For example, the fixing member
70 may be fixed to the bearing housing 22 by shrink-fitting. The
intermediate portion 221 is a section in which the thickness of the
bearing housing 22 in the radial direction is larger than that at
the first bearing holding portion 501. The intermediate portion 221
has strength sufficient for fixing of the fixing member 70 by
press-fitting. If the fixing member 70 is fixed to a portion, such
as the first bearing holding portion, having a thin thickness in
the radial direction, there is a possibility that the bearing
housing 22 is deformed and the bearings 23 are also deformed. If
the bearings 23 are subjected to deformation and stress, there is a
possibility that the lifetime of the bearings 23 is affected.
Therefore, it is possible to suppress deformation of the bearing
housing 22 by fixing the fixing member 70 to the intermediate
portion 221, which has sufficient strength.
In the present embodiment, the fixing member 70 is formed of a
non-magnetic metal material and is a ring member that has an
annular shape. Preferably, the material of the fixing member 70 is
identical to that of the bearing housing 22. For example, a copper
alloy material such as brass is used as the material of the bearing
housing 22 and the fixing member 70. It is possible to prevent the
fixing member 70 from coming off from the bearing housing 22 during
heat-curing of the adhesive and an elastic member 71, which will be
described later by using materials having identical linear
expansion coefficients for the bearing housing 22 and the fixing
member 70. Moreover, it is possible to fix the stator 24 to a
predetermined location in the bearing housing 22, and thus, it is
possible to suppress the displacement between the bearing housing
22 and the stator 24. Each of the bearing housing 22 and the fixing
member 70 may be formed of a metal material, such as aluminum, or
resin. In addition, it is possible to suppress a magnetic effect on
the stator core 41 by using a non-magnetic metal material.
Further, it is possible to firmly fix the stator 24 to the bearing
housing 22 by using a ring-shaped annular member as the fixing
member 70. The fixing member 70 that has a ring shape is formed by
cutting a rod-shaped or pipe-shaped metal material. The ring-shaped
fixing member 70 may be formed by punching a plate-shaped
material.
As illustrated in FIGS. 2, 3, and 4, the outer circumferential
surface of the bearing housing 22 according to the present
embodiment includes the step surface 222 that has a circular ring
shape. The step surface 222 extends outward in the radial direction
from a lower end portion of the first outer circumferential surface
51. A portion of the step surface 222 and a portion of the lower
surface of the stator core 41 are opposite each other in the axial
direction. The radius of the outer edge of the fixing member 70
with the center axis 9 as the center is larger than the radius of
the outer edge of the step surface 222. The step surface 222
restricts the downward displacement of the stator 24 in the axial
direction relative to the bearing housing 22.
The fixing member 70 is disposed above the stator 24. The stator 24
is disposed above the step surface 222 of the bearing housing 22.
That is, the stator 24 is held by the fixing member 70 and the step
surface 222 of the bearing housing 22 so as to be therebetween in
the vertical direction, and fixed to the bearing housing 22 in this
state. It is possible to suppress the displacement of the stator 24
relative to the bearing housing 22 by restricting the vertical
movement of the stator 24.
In the present embodiment, the fixing member 70 is disposed above
the stator core 41. The lower surface of the fixing member 70 is in
contact with the upper surface of the stator core 41. In other
embodiments, the lower surface of the fixing member 70 may be in
contact with the upper surface of the insulator 42.
As illustrated in FIG. 3, the bearing housing 22 is opposite the
stator core 41 in the radial direction with a gap 414 therebetween.
The gap 414 is filled with the elastic member 71. Specifically, the
elastic member 71 is interposed between the first outer
circumferential surface 51 of the bearing housing 22 and the inner
circumferential surface of the stator core 41. The elastic member
71 is, for example, a silicon-based elastic adhesive. The elastic
member 71 has a function of fixing the stator core 41 to the
bearing housing 22 and a function of absorbing vibration generated
in the stator core 41. Transmission of vibration from the stator
core 41 to the bearing housing 22 is suppressed by using the
elastic member 71. As a result, vibration and noise during driving
of the motor 1 is reduced.
The elastic member 71, however, sometimes takes a long time for
curing after application. Thus, it is required to prevent the
displacement of the stator 24 relative to the bearing housing 22
after the elastic member 71 is applied until the elastic member 71
is cured. In the present embodiment, as described above, the lower
surface of the fixing member 70 is in contact with the upper
surface of the stator core 41. In addition, the inner
circumferential surface of the fixing member 70 is in contact with
the first outer circumferential surface 51 of the bearing housing
22. Thus, it is possible to suppress the displacement of the stator
24 relative to the bearing housing 22 during curing of the elastic
member 71.
As illustrated in FIG. 3, the fixing member 70 covers the upper
side of the gap 414. Specifically, the outer diameter of the fixing
member 70 is larger than the gap 414, which is opposite the bearing
housing 22 and the stator core 41 in the radial direction. The
fixing member 70 that is large enough to cover the upper side of
the gap 414 makes it possible to prevent the elastic member 71 from
flowing out from the upper portion of the stator 24 during curing
of the elastic member 71. In addition, it is possible to retain the
elastic member 71 inside the gap 414.
As illustrated in FIG. 5, the stator core 41 according to the
present embodiment includes a plurality of recessed portions 413 in
the inner circumferential surface thereof. The plurality of
recessed portions 413 are arranged at equal spaces in the
circumferential direction. Each of the recessed portions 413 is
recessed outward in the radial direction from the inner
circumferential surface of the stator core 41. A portion of the
elastic member 71 is positioned inside the recessed portions 413.
Providing the inner circumferential surface of the stator core 41,
as described above, with the recessed portions 413 that retain the
elastic member 71 makes it possible to suppress variation in the
amount of the elastic member 71 that is interposed between the
bearing housing 22 and the stator core 41. The inner
circumferential surface of the stator core 41 is in direct contact,
at a portion thereof other than the recessed portions 413, with the
first outer circumferential surface 51 of the bearing housing 22.
As a result, it is possible to position the stator core 41 relative
to the bearing housing 22 with higher accuracy. However, the
portion other than the recessed portions 413 of the inner
circumferential surface of the stator core 41 is not necessarily in
direct contact with the first outer circumferential surface 51 of
the bearing housing 22; a gap may be interposed therebetween. In
addition, the elastic member 71 may be disposed in the gap.
As illustrated in FIG. 3, a portion of the elastic member 71 may be
interposed between the lower surface of the stator core 41 and the
step surface 222. As a result, transmission of vibration from the
lower surface of the stator core 41 to the bearing housing 22 is
suppressed. Therefore, it is possible to further reduce vibration
and noise during driving of the motor 1.
As illustrated in each of FIG. 3 and FIG. 4, the stator 24 has, on
the upper surface thereof, an annular groove portion 421 that is
recessed downward in the axial direction. In the present
embodiment, the groove portion 421 is a portion surrounded by the
first outer circumferential surface 51, which is the outer
circumferential surface of the bearing housing 22, the upper
surface of the stator core 41, and the inner surface of the
insulator 42. At least a portion of the fixing member 70 is housed
in the groove portion 421. The lower surface of the fixing member
70 is in contact with the upper surface of the stator core 41.
Providing the groove portion 421 on the upper side of the stator 24
and housing the fixing member 70 inside the groove portion 421
enable a reduction in the thickness of the motor. For example, the
fixing member 70 is positioned inside the coil 43 in the radial
direction. A gap between the bearing housing 22 and the coil 43 in
the radial direction is a void in the structure of the motor 1.
Disposing the fixing member 70 in the void makes it possible to fix
the stator 24, at a position lower than the height of the coil 43
in the axial direction, to the bearing housing 22. As a result, it
is possible to reduce the thickness of the motor 1.
One embodiment as an example of the present disclosure is described
above; however, the present disclosure is not limited to the
aforementioned embodiment.
FIG. 6 is a perspective view of a bearing housing 22A, a stator
24A, and a fixing member 70A according to one modification as an
example. In the example in FIG. 6, the fixing member 70A is a
member that has a ring shape in which a portion is partially
broken. Namely, the ring shape is a C-ring shape in which a portion
is open. It is possible to reduce pressure of press fitting the
fixing member 70A to the bearing housing 22A by employing the C
ring shape for the fixing member 70A. A reduction in the pressure
of press fitting makes it possible to dispose the fixing member 70A
at an appropriate location in the stator 24A by preventing the
fixing member 70A from separating from the stator 24A.
In the aforementioned embodiment, the elastic adhesive is
interposed between the bearing housing and the stator core.
However, an adhesive of a different type may be disposed between
the bearing housing and the stator core. Moreover, the bearing
housing and the stator core may be in direct contact with each
other with no adhesive interposed therebetween. However, in a case
in which an adhesive, such as an elastic adhesive or a heat-curable
adhesive, that takes a long time for curing is used, it is required
to suppress the displacement of the stator core relative to the
bearing housing until the curing is completed. Therefore, the
present disclosure is particularly useful.
In addition, as illustrated in FIG. 4 and FIG. 5, the recessed
portions 413 recessed outward in the radial direction from the
inner circumferential surface of the stator core 41 may be recessed
outward in the radial direction further than the outer edge of the
step surface 222. In this case, the gap 414 between the bearing
housing 22 and the stator core 41 extends toward the lower side of
the stator core 41. The gap 414 forms a through hole that extends
to the lower surface of the stator core 41, which makes it possible
to control the amount of the elastic member 71. Namely, it is
possible to discharge an excessive amount of the elastic member 71
to the outside of the gap 414 through the through hole when the
elastic member 71 of an amount more than the space volume of the
gap 414 is applied.
The application of the motor according to the present disclosure is
not particularly limited. The motor according to the present
disclosure may be, for example, a fan motor that includes an
impeller attached to a rotary portion.
The shape of each of small portions of each member may differ from
the shape illustrated in the drawings of the present disclosure.
The components presented in the embodiment and the modification
described above may be combined together, as appropriate, as long
as there is no inconsistency.
Features of the above-described preferred embodiments and the
modifications thereof may be combined appropriately as long as no
conflict arises.
While preferred embodiments of the present disclosure have been
described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the present disclosure. The
scope of the present disclosure, therefore, is to be determined
solely by the following claims.
* * * * *